EXPERIMENTAL TECHNIQUES

Carbon dioxide is slightly soluble in water while hydrogen chloride is verysoluble in water. Which diagram represents the correct method of obtaining dry carbondioxide from a mixture of moist carbon dioxide and hydrogen chloride?

A

B

C

B

Correct!

Wrong!

A round-bottom flask consists of a mixture of liquids. Which graph best shows the change in mass of the liquid with the lowest boiling point in the flask as the mixture is being distilled?

A

B

C

D

Correct!

Wrong!

Which of the following methods is best used to obtain solid samples of each from a mixture of iodine crystals and diamond?

dissolving > filtration > crystallization

sublimation > deposition

sublimation > condensation

dissolving > filtration > evaporation to dryness

Correct!

Wrong!

A mixture of alkanes was separated into components using the following apparatus. The first fraction collected is fraction X, then fraction Y. From this information we can deduce that

Fraction X is more volatile than Y.

Fraction X has a higher molar mass than Y.

Fraction X has a higher boiling point than

Fraction X has weaker covalent bonds in its molecules than Y.

Correct!

Wrong!

Chromatography s used to separate amino acids in proteins. The chromatogram of protein X is shown. Which amino acids are found in X and which amino acid has the largest Rf value?

A

B

C

D

Correct!

Wrong!

Which mixture will leave no residue when heated in an evaporating dish?

Aqueous potassium chloride

Copper(II) carbonate powder and iodine crystals

Hydrated copper(II) sulfate and sodium chloride crystals

Iodine crystals mixed with ammonium chloride

Correct!

Wrong!

A bottle containing solid barium sulfate was found to be contaminated with solid barium nitrate. How can barium nitrate be removed to leave a pure sample of barium sulfate?

Chromatography

Filtration

Sublimation

Distillation

Correct!

Wrong!

Which of the following property can be used to check for the purity of afood dye?